From ecba7133ffef32b817d53bcb2ceeb3113b37bb07 Mon Sep 17 00:00:00 2001
From: Bas van Beek <b.f.van.beek@vu.nl>
Date: Sun, 5 Sep 2021 23:46:34 +0200
Subject: MAINT: Let `_remove_nan_1d` attempt to identify nan-containing object
 arrays

Use the same approach as in numpy/numpy#9013
---
 numpy/lib/nanfunctions.py | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

(limited to 'numpy/lib/nanfunctions.py')

diff --git a/numpy/lib/nanfunctions.py b/numpy/lib/nanfunctions.py
index 46c71e1f5..766bf3c82 100644
--- a/numpy/lib/nanfunctions.py
+++ b/numpy/lib/nanfunctions.py
@@ -161,9 +161,11 @@ def _remove_nan_1d(arr1d, overwrite_input=False):
         input
     """
     if arr1d.dtype == object:
-        return arr1d, True
+        # object arrays do not support `isnan` (gh-9009), so make a guess
+        c = np.not_equal(arr1d, arr1d, dtype=bool)
+    else:
+        c = np.isnan(arr1d)
 
-    c = np.isnan(arr1d)
     s = np.nonzero(c)[0]
     if s.size == arr1d.size:
         warnings.warn("All-NaN slice encountered", RuntimeWarning,
-- 
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